Gracefully handle transformers rejecting their configuration.

sdk/lib/_internal/pub/test/transformer/a_transformer_rejects_its_config_test.dart

Index: sdk/lib/_internal/pub/test/transformer/a_transformer_rejects_its_config_test.dart
diff --git a/sdk/lib/_internal/pub/test/transformer/fails_to_load_an_unconfigurable_transformer_when_config_is_passed_test.dart b/sdk/lib/_internal/pub/test/transformer/a_transformer_rejects_its_config_test.dart
similarity index 52%
copy from sdk/lib/_internal/pub/test/transformer/fails_to_load_an_unconfigurable_transformer_when_config_is_passed_test.dart
copy to sdk/lib/_internal/pub/test/transformer/a_transformer_rejects_its_config_test.dart
index 9e18ce540aa71bc808e97c4f01ee121f8b2bdcec..caa0c95be8af829030039542c4c5b043d000405a 100644
--- a/sdk/lib/_internal/pub/test/transformer/fails_to_load_an_unconfigurable_transformer_when_config_is_passed_test.dart
+++ b/sdk/lib/_internal/pub/test/transformer/a_transformer_rejects_its_config_test.dart
@@ -1,4 +1,4 @@
-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS d.file
+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS d.file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
@@ -10,27 +10,41 @@ import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import '../serve/utils.dart';
 
+const REJECT_CONFIG_TRANSFORMER = """
+import 'dart:async';
+
+import 'package:barback/barback.dart';
+
+class RejectConfigTransformer extends Transformer {
+  RejectConfigTransformer.asPlugin(BarbackSettings settings) {
+    throw "I hate these settings!";
+  }
+
+  Future<bool> isPrimary(_) => new Future.value(true);
+  Future apply(Transform transform) {}
+}
+""";
+
 main() {
   initConfig();
 
   withBarbackVersions("any", () {
-     integration("fails to load an unconfigurable transformer when config is "
-         "passed", () {
+     integration("a transformer can reject is configuration", () {
        d.dir(appPath, [
          d.pubspec({
            "name": "myapp",
            "transformers": [{"myapp/src/transformer": {'foo': 'bar'}}]
          }),
          d.dir("lib", [d.dir("src", [
-           d.file("transformer.dart", REWRITE_TRANSFORMER)
+           d.file("transformer.dart", REJECT_CONFIG_TRANSFORMER)
          ])])
        ]).create();
 
        createLockFile('myapp', pkg: ['barback']);
 
        var pub = startPubServe();
-       pub.stderr.expect(startsWith('No transformers that accept configuration '
-           'were defined in '));
+       pub.stderr.expect(endsWith('Error loading transformer: I hate these '
+           'settings!'));
        pub.shouldExit(1);
      });
   });